First off this new Memphis ownership seems concerned with saving their money for the future as seen by the Rudy Gay trade. Getting Jennings, Dalembert and Augustin would support this as all are playing on expiring contracts. Jennings would give Gasol and Z-Bo easy pts in the paint, Dalembert would give Memphis a center (something Coach Hollins wants a lot) and a back-up point guard in Augustin, a position the Grizzlies really need to fill. Thus this trade still makes the Grizzlies competitive while saving cash.

Milwaukee needs to split this Jennings and Ellis duo up as each player needs the ball in their hands to be effective. Trading Jennings and getting Granger would give the Bucks a 20 plus point scorer who doesn't need the ball in his hands to produce on the court. Granger is also a three pt threat that Milwaukee could really use. Allen would shore-up the defense at the SG, no longer making it a mismatch for the Bucks in terms of defense. The trade would help Milwaukee be more competitive come playoff time.

Finally, Indiana gets a real point guard in Conley and would let George Hill slide over to SG where he is a more natural fit. Adding Mbah a Moute would made Indiana's defense even better (a scary thought). Stephenson would be able to play back-up PG Indiana would look like a contender in the East.

After Memphis got under the cap the motive behind trading Gay was a Hollinger analytics decision.
Conley is a better PG then Jennings. Jennings will be looking for a contract equal to or better then the one Conley has which is 12/13 $7,180,000 13/14 $7,900,000 14/15 $8,760,000 15/16 $9,680,000
Tony Allen is an expiring 3.3 mi deal... likely looking for a raise.
Memphis will decline Austin Dayes 4.14 mil qualifing offer and use the money to pay Allen.
Dalembert will need to be resigned at an affordable contract, (he makes 6.7 this season)
Augustin is not a championship PG and will also be looking for the best contract out there.

So why would Memphis trade Conley, who is a pretty sweet PG on a reasonable contract and Tony Allen for Dalembert, Jennings and Augustin? 3 players they are unlikely to be retained affordably in the offseason UFA market. If Memphis wants Dalembert they should just wait untill the offseason and make an offer for free imo.